OS: Arch Linux
WM: i3
xdg-utils @ 6da906f

Trying to open a file:// URL containing an URL fragment gives an error:

$ ls $(pwd)/*.html
/home/miki/index.html
$ XDG_UTILS_DEBUG_LEVEL=3 xdg-open "file://$(pwd)/index.html#anchor"
Selected DE generic
xdg-open: file '/home/miki/index.html#anchor' does not exist

A real-world example of this problem is Dropbox, where choosing "Launch Dropbox Website" from the menu leads to a similar error.

Even setting the default handler for file:// URLS doesn't solve the problem:

$ xdg-mime default chromium.desktop x-scheme-handler/file
$ xdg-mime query default x-scheme-handler/file
chromium.desktop
$ XDG_UTILS_DEBUG_LEVEL=3 xdg-open "file://$(pwd)/index.html#anchor"
Selected DE generic
xdg-open: file '/home/miki/index.html#anchor' does not exist

The browser handles these URLs without problems:
$ chromium "file://$(pwd)/index.html#anchor"
(browse away)

Specifying URL fragments (f.i. as 'anchors') is a very useful feature which xdg-open should not interfere with, IMHO.
In particular, when user sets a default handler for file:// URLs, xdg-open should honor that.